Single-layer ceramic-based knit fabric for high temperature bulb seals

ABSTRACT

Knit fabrics having ceramic strands, thermal protective members formed therefrom and to their methods of construction are disclosed. Methods for fabricating thermal protection using multiple materials which may be concurrently knit are also disclosed. This unique capability to knit high temperature ceramic fibers concurrently with a load-relieving process aid, such as an inorganic or organic material (e.g., metal alloy or polymer), both small diameter wires within the knit as well as large diameter wires which provide structural support and allow for the creation of near net-shape preforms at production level speed. Additionally, ceramic insulation can also be integrated concurrently to provide increased thermal protection.

FIELD

The implementations described herein generally relate to knit fabricsand more particularly to single-layer knit fabrics having ceramicstrands knit concurrently with metal wire, thermal sealing membersformed therefrom and to their methods of construction.

BACKGROUND

In many high-temperature applications, such as aircraft structures,thermal sealing members are often utilized between opposing faces orparts. These opposing parts may be opened and closed repeatedly duringoperation or maintenance procedures. Typically the thermal sealingmember provides a thermal barrier that will withstand particularconditions, for example, an exposure to temperatures in excess of 1,000degrees Celsius for in excess of 15 minutes.

Current techniques for manufacturing thermal sealing members include theuse of multilayer materials including, for example, stainless steelspring tube, multiple layers of woven ceramic fabric, and an outerstainless steel mesh that must be integrated by hand. Beyond thefabrication challenges, stiffness of the stainless steel spring tube isrelatively low, which can lead to wrinkling, deformations, andsubsequently degraded performance at critical regions. In addition, thecurrent thermal sealing members typically known as “bulb seals,” arerepeatedly compressed in normal use, and do not restore to their propershape and maintain the seal. Furthermore, current thermal sealingmembers often have marginal thermal resistance and burn out in anexcessively short time. The capability of being compressed manythousands of times while still providing a good thermal barrier is thusdifficult to achieve.

Therefore there is a need for improved light-weight, low cost and highertemperature capable thermal sealing members that permit higheroperational temperatures while minimizing compression set under thermalloads and methods of manufacturing the same.

SUMMARY

The implementations described herein generally relate to knit fabricsand more particularly to single-layer knit fabrics having ceramicstrands knit concurrently with metal wire, thermal sealing membersformed therefrom and to their methods of construction. According to oneimplementation, a thermal sealing member is provided. The thermalsealing member comprises a single-layer ceramic-based knit fabric and afirst metal alloy wire. The single-layer ceramic-based knit fabriccomprises a continuous ceramic strand and a continuous load-relievingprocess aid strand. The continuous ceramic strand serves the continuousload-relieving process aid strand. The continuous load-relieving processaid strand and the first metal alloy wire are concurrently knit to formthe single-layer ceramic-based knit fabric. The continuousload-relieving process aid strand may be a polymeric material. Thecontinuous load-relieving process aid strand may be a metallic material.The continuous ceramic strand may be a multifilament material and thecontinuous load-relieving process aid strand may be a monofilamentmaterial.

In some implementations, the thermal sealing member further comprises asecond metal alloy wire inlayed into the ceramic-based knit fabric. Thesecond metal alloy wire may be interwoven into the ceramic-based knitfabric. A diameter of the second metal alloy wire may be greater than adiameter of the first metal alloy wire. The second metal alloy wire maybe shaped such that there is uniform spacing, non-uniform spacing, orboth uniform and non-uniform spacing between segments of the secondmetal alloy wire to achieve a tailored stiffness. The tailored stiffnessis specific to the application with respect to both geometry andoperational loads. In some implementations, the second metal alloy wireis aligned parallel with a knit direction of the single-layerceramic-based knit fabric. In some implementations, the second metalalloy wire is angled relative to a knit direction of the single-layerceramic-based knit fabric. In some implementations, multiple metal alloywires are inlayed in the ceramic-based knit fabric. In someimplementations, the multiple metal alloy wire inlays include at leastone inlay aligned with the knit direction and at least one inlay angledrelative to the knit direction. The metal wire alloys may be designed,aligned or both such that at least one of the cross-overs orintersections of the inlaid metal alloy wires occur away from contact orabrasive surfaces in order to mitigate seal wear.

In some implementations, the metal alloy wires may be designed, alignedor both such that at least one of the cross-overs or intersections ofthe inlaid metal alloy wires occur outside of the knit fabric away fromcontact or abrasive surfaces in order to mitigate seal wear.

In some implementations, the single-layer ceramic-based knit fabric isconstructed using a flat-knitting process or a tubular-knitting process.The single-layer ceramic-based knit fabric may be a weft-knitted fabric.The single-layer ceramic-based knit fabric may be a warp-knitted fabric.

In some implementations, the thermal sealing member further comprisesinsulation material positioned in an interior of the thermal sealingmember. The insulation material may be stitched to the single-layerceramic-based knit fabric.

In some implementations, the thermal sealing member is selected from anM-shaped double-blade bulb seal, an omega-shaped bulb seal, and ap-shaped bulb seal.

In some implementations, the thermal sealing member is made from shapingthe single-layer ceramic-based knit fabric into an M-shaped double-bladebulb seal, an omega-shaped bulb seal, or a p-shaped bulb seal.

In some implementations, the thermal sealing member has a reversibleelastic deflection of at least 10% to at most 80% of a height of thethermal sealing member.

In yet another implementation, a method of forming a thermal sealingmember is provided. The method comprises simultaneously feeding acontinuous ceramic strand and a continuous load-relieving process aidstrand through a single material feeder and a first metal alloy wirethrough a second material feeder. The ceramic strand, the continuousload-relieving process aid strand and the first metal alloy wire areconcurrently knit or “plated” together to form a single-layerceramic-based knit fabric. The metal alloy wire may be in asoft-tempered state. The single-layer ceramic-based knit fabric isformed into the shape of the thermal sealing member. The metal alloywire may be heat hardened after the final seal shape is achieved. Themethod may further comprise wrapping the continuous ceramic strandaround the continuous process aid strand prior to simultaneously feedingthe continuous ceramic strand and the continuous load-relieving processaid strand into the knitting machine. The method may further compriseheating the knit fabric to a first temperature to remove theload-relieving process aid. The method may further comprise heating theknit fabric to a second temperature greater than the first temperatureto anneal the ceramic strand. The method may further comprise removingthe continuous load-relieving process aid strand from the knit fabric.The load-relieving process aid may be removed by exposure to a solvent,heat or light to remove the process aid.

In some implementations, the method further comprises interweaving asecond metal alloy wire into the ceramic-based knit fabric. The diameterof the second metal alloy wire may be greater than a diameter of thefirst metal alloy wire. The second metal alloy wire may be alignedparallel with a knit direction of the single-layer ceramic-based knitfabric. The second metal alloy wire may be angled relative to a knitdirection of the single-layer ceramic-based knit fabric.

In some implementations, the method further comprises adding insulationmaterial to an interior of the shaped thermal sealing member. Theinsulation material may be stitched to the single-layer ceramic-basedknit fabric. The single-layer ceramic-based knit fabric may be stitchedtogether to form the thermal sealing member.

In some implementations, concurrent knitting is performed using either aflat-knitting process or a tubular-knitting process. The single-layerceramic-based knit fabric may be formed using a weft-knitting process.The single-layer ceramic-based knit fabric may be formed using awarp-knitting process. The method may further comprise heat treating theformed thermal sealing member to remove the load-relieving process aid.The method may further comprise heat treating the formed thermal sealingmember to harden the first metal alloy wire.

The features, functions, and advantages that have been discussed can beachieved independently in various implementations or may be combined inyet other implementations, further details of which can be seen withreference to the following description and drawings.

BRIEF DESCRIPTION OF ILLUSTRATIONS

So that the manner in which the above-recited features of the presentdisclosure can be understood in detail, a more particular description ofthe disclosure briefly summarized above may be had by reference toimplementations, some of which are illustrated in the appended drawings.It is to be noted, however, that the appended drawings illustrate onlytypical implementations of this disclosure and are therefore not to beconsidered limiting of its scope, for the disclosure may admit to otherequally effective implementations.

FIG. 1 is an enlarged partial perspective view of a multicomponentstranded yarn including a continuous ceramic strand and a continuousload-relieving process aid strand prior to processing according toimplementations described herein;

FIG. 2 is an enlarged partial perspective view of a multicomponentstranded yarn including a continuous ceramic strand wrapped around acontinuous load-relieving process aid strand according toimplementations described herein;

FIG. 3 is an enlarged partial perspective view of a multicomponentstranded yarn including a continuous ceramic strand, a continuousload-relieving process aid strand and a metal alloy wire prior toprocessing according to implementations described herein;

FIG. 4 is an enlarged partial perspective view of a multicomponentstranded yarn including a continuous ceramic strand wrapped around acontinuous load-relieving process aid strand and a metal alloy wireaccording to implementations described herein;

FIG. 5 is an enlarged perspective view of one example of a knit fabricthat includes a multicomponent yarn and a fabric integrated inlayaccording to implementations described herein;

FIG. 6 is an enlarged perspective view of yet another example of a knitfabric that includes a multicomponent yarn and a fabric integrated inlayaccording to implementations described herein;

FIG. 7 is an enlarged perspective view of yet another example of a knitfabric that includes a multicomponent yarn and multiple fabricintegrated inlays according to implementations described herein;

FIG. 8 is a process flow diagram for forming a thermal sealing memberaccording to implementations described herein;

FIG. 9 is a schematic cross-sectional view of an exemplary thermalsealing member according to implementations described herein;

FIGS. 10A-10B are schematic cross-sectional views of another thermalsealing member according to implementations described herein; and

FIGS. 11A-11B are schematic cross-sectional views of another thermalsealing member according to implementations described herein.

To facilitate understanding, identical reference numerals have beenused, wherever possible, to designate identical elements that are commonto the figures. Additionally, elements of one implementation may beadvantageously adapted for utilization in other implementationsdescribed herein.

DETAILED DESCRIPTION

The following disclosure describes knit fabrics and more particularlydescribes single-layer knit fabrics having ceramic strands knitconcurrently with metal wire, thermal sealing members formed therefromand to their methods of construction. Certain details are set forth inthe following description and in FIGS. 1-11 to provide a thoroughunderstanding of various implementations of the disclosure. Otherdetails describing well-known structures and systems often associatedwith knit fabric types and architectures and forming knit fabrics arenot set forth in the following disclosure to avoid unnecessarilyobscuring the description of the various implementations.

Many of the details, dimensions, angles and other features shown in theFigures are merely illustrative of particular implementations.Accordingly, other implementations can have other details, materials,components, dimensions, angles and features without departing from thespirit or scope of the present disclosure. In addition, furtherimplementations of the disclosure can be practiced without several ofthe details described below.

Prior to the implementations described herein, it was not feasible toproduce products having complex geometries or near net-shape componentsby knitting multiple materials into a single-layer at production levelspeeds. Current techniques for producing high temperature seals includemultilayer solutions having stainless steel spring tube, multiple layersof woven ceramic and an outer stainless steel mesh that must beintegrated by hand. Beyond the fabrication challenges, the stainlesssteel spring tube stiffness is relatively low, which can lead towrinkling, deformations, and subsequently to degraded performance atcritical regions of the formed component. Thus, current fabricationtechniques fail to address the fundamental issues of producing lighterweight, efficient, and low cost thermal barrier seals that permit higheroperation temperatures while minimizing compression set under thermalloads. The unique capability to knit high temperature ceramic fibersconcurrently with metal alloy wire, both small diameter wire within theknit fabric as well as large diameter wire which provides structuralsupport, creates complex near net-shape preforms at production-levelspeed with improved compression set at thermal loads.

Some implementations described herein relate to methods for fabricatingthermal protection using multiple materials which may be concurrentlyknit with commercially available knitting machines. This uniquecapability to knit high temperature ceramic fibers concurrently with aload-relieving process aid, such as an inorganic or organic material(e.g., metal alloy or polymer), both small diameter wire (e.g., fromabout 50 micrometers to about 300 micrometers; from about 100micrometers to about 200 micrometers) within the knit as well as largediameter wire (e.g., from about 300 micrometers to about 1,000micrometers; from about 400 micrometers to about 700 micrometers). Theload-relieving process aid provides structural support and de-tensionsthe ceramic fiber as the ceramic fiber is exposed to the stresses of thesmall radius curvature present in commercial knitting machines. Thus,the creation of near net-shape performs comprising ceramic fibers atproduction level speed can be achieved. Additionally, ceramic insulationcan also be integrated concurrently to provide increased thermalprotection. Not to be bound by theory, it is believed that the largediameter wire enhances the bending stiffness and the small diameter wirecontributes to the abrasion resistance of the co-knit fabric. Both thelarge diameter wire and the small diameter wire are sized appropriatelyfor their function. The diameter of the small diameter wire is typicallyselected such that it does not interfere with the bending stiffnessenhancement provided by the large diameter wire. In someimplementations, there is at least a 50% difference (e.g., between 50%and 70% difference; between 55% and 65% difference) between the diameterof the small wire and the diameter of the large wire.

In addition, some implementations described herein also include afabrication process for knit thermal protection materials using acommercially available knitting machine. Unlike previous work, someimplementations described herein include multiple materials beingconcurrently knit in a single-layer. The materials and knit parametersmay be varied in order to produce a tailorable part for a specificapplication. Some implementations described herein generally differ fromprevious techniques by providing at least one of the followingadvantages: enables higher operating temperature engines; reducescertification effort and time; and reduces process fabrication andmaintenance costs.

In some implementations described herein, multiple materials (e.g.,ceramic fibers and alloy wires) are concurrently knit in a single knitlayer. Concurrently knitting in a single-layer may save weight,fabrication and assembly labor for registration of layers. In someimplementations, the knit surrounds an inlaid larger diameter wire whichserves to resist an applied mechanical force.

The implementations described herein are potentially useful across abroad range of products, including many industrial products andaero-based owner products (subsonic, supersonic and space), which wouldsignificantly benefit from lighter-weight, low cost, and highertemperature capable shaped components. These components include but arenot limited to a variety of soft goods such as, for example, thermallyresistant seals, gaskets, expansion joints, blankets, wiring insulation,tubing/ductwork, piping sleeves, firewalls, insulation for thrustreversers, engine struts and composite fan cowls. These components alsoinclude but are not limited to hard goods such as exhaust and enginecoverings, liners, shields and tiles.

In some implementations, the thermal sealing member has a reversibleelastic deflection of at least 10% to at most 80% of a height of thethermal sealing member (e.g., at least 20% to at most 70%; at least 30%to at most 60%). Not to be bound by theory, it is believed that thereversible elastic deflection of the thermal sealing member is directlyrelated to the elastic strength/strain limits of the bending material.Further, in implementations where Inconel® alloy 718 is used, it isbelieved that heat treatment of the Inconel® alloy 718 increases thestrength to enable large elastic deflections.

The methods for fabricating knit thermal protection described herein maybe performed using commercially-available knitting machines. In someimplementations, a sacrificial monofilament may be used as a knitprocessing aid to prevent breakage of the ceramic fiber. The sacrificialmonofilament may be removed after the component is knit. Additionally,in some implementations, a metal alloy component may be “plated” withthe ceramic yarn into the desired knit fabric.

The materials described herein can also be knit into net-shapes andfabrics containing spatially differentiated zones, both simple andcomplex, directly off the machine through conventional bind off andother apparel knitting techniques. Exemplary net-shapes include simplebox-shaped components, complex curvature variable diameter tubularshapes, and geometric tubular shapes.

The term “filament” as used herein refers to a fiber that comes incontinuous or near continuous length. The term “filament” is meant toinclude monofilaments and/or multifilament, with specific referencebeing given to the type of filament, as necessary.

The term “flexible” as used herein means having a sufficient pliabilityto withstand small radius bends, or small loop formation withoutfracturing, as exemplified by not having the ability to be used institch bonding or knitting machines without substantial breakage.

The term “heat fugitive” as used herein means volatizes, burns ordecomposes upon heating.

The term “knit direction” as used herein is vertical duringwarp-knitting and horizontal during weft-knitting.

The term “strand” as used herein means a plurality of aligned,aggregated fibers or filaments.

The term “yarn” as used herein refers to a continuous strand or aplurality of strands spun from a group of natural or synthetic fibers,filaments or other materials which can be twisted, untwisted or laidtogether.

Referring in more detail to the drawings, FIG. 1 is an enlarged partialperspective view of a multicomponent stranded yarn 100 including acontinuous ceramic strand 110 and a continuous load-relieving processaid strand 120 prior to processing according to implementationsdescribed herein. The continuous load-relieving process aid strand 120is typically under tension during the knitting process while reducingthe amount of tension that the continuous ceramic strand is subjected toduring the knitting process. As depicted in FIG. 1, the multicomponentstranded yarn 100 is a bi-component stranded yarn.

The continuous ceramic strand 110 may be a high temperature resistantceramic strand. The continuous ceramic strand 110 is typically resistantto temperatures greater than 500 degrees Celsius (e.g., greater than1,200 degrees Celsius). The continuous ceramic strand 110 typicallycomprises multi-filament inorganic fibers. The continuous ceramic strand110 may comprise individual ceramic filaments whose diameter is about 15micrometers or less (e.g., 12 micrometers or less; a range from about 1micron to about 12 micrometers) and with the yarn having a denier in therange of about 50 to 2,400 (e.g., a range from about 200 to about 1,800;a range from about 400 to about 1,000). The continuous ceramic strand110 can be sufficiently brittle but not break in a small radius bend ofless than 0.07 inches (0.18 cm). In some implementations, a continuouscarbon-fiber strand may be used in place of the continuous ceramicstrand 110.

Exemplary inorganic fibers include inorganic fibers such as fused silicafiber (e.g., Astroquartz® continuous fused silica fibers) ornon-vitreous fibers such as graphite fiber, silicon carbide fiber (e.g.,Nicalon™ ceramic fiber available from Nippon Carbon Co., Ltd. of Japan)or fibers of ceramic metal oxide(s) (which can be combined withnon-metal oxides, e.g., SiO₂) such as thoria-silica-metal (III) oxidefibers, zirconia-silica fibers, alumina-silica fibers,alumina-chromia-metal (IV) oxide fiber, titania fibers, andalumina-boria-silica fibers (e.g., 3M™ Nextel™ 312 continuous ceramicoxide fibers). These inorganic fibers may be used for high temperatureapplications. In implementations where the continuous ceramic strand 110comprises alumina-boria-silica yarns, the alumina-boria-silica maycomprise individual ceramic filaments whose diameter is about 8micrometers or less with the yarn having a denier in the range of about200 to 1,200.

The continuous load-relieving process aid strand 120 may be amonofilament or multi-filament strand. The continuous load-relievingprocess aid strand 120 may comprise organic (e.g., polymeric), inorganicmaterials (e.g., metal or metal alloy) or combinations thereof. In someimplementations, the continuous load-relieving process aid strand 120 isflexible. In some implementations, the continuous load-relieving processaid strand 120 has a high tensile strength and a high modulus ofelasticity. In implementations where the continuous load-relievingprocess aid strand 120 is a monofilament, the continuous load-relievingprocess aid strand 120 may have a diameter from about 100 micrometers toabout 625 micrometers (e.g., from about 150 micrometers to about 250micrometers; from about 175 micrometers to about 225 micrometers). Inimplementations where the continuous load-relieving process aid strand120 is a multifilament, the individual filaments of the multifilamentmay each have a diameter from about 10 micrometers to about 50micrometers (e.g., from about 20 micrometers to about 40 micrometers).

Depending on the application, the continuous load-relieving process aidstrand 120, whether multifilament or monofilament, can be formed from,by way of example and without limitation, from polyester, polyamide(e.g., Nylon 6,6), polyvinyl acetate, polyvinyl alcohol, polypropylene,polyethylene, acrylic, cotton, rayon, and fire retardant (FR) versionsof all the aforementioned materials when extremely high temperatureratings are not required. If higher temperature ratings are desiredalong with FR capabilities, then the continuous load-relieving processaid strand 120 could be constructed from, by way of example and withoutlimitation, materials including meta-Aramid fibers (sold under namesNomex®, Conex®, for example), para-Aramid (sold under the tradenamesKevlar®, Twaron®, for example), polyetherimide (PEI) (sold under thetradename Ultem®, for example), polyphenylene sulfide (PPS), liquidcrystal thermoset (LCT) resins, polytetrafluoroethylene (PTFE), andpolyether ether ketone (PEEK). When even higher temperature ratings aredesired along with FR capabilities, the continuous load-relievingprocess aid strand 120 can include mineral yarns such as fiberglass,basalt, silica and ceramic, for example. Aromatic polyamide yarns andpolyester yarns are illustrative yarns that can be used as thecontinuous load-relieving process aid strand 120.

In some implementations, the continuous load-relieving process aidstrand 120, when made of organic fibers, may be heat fugitive, i.e., theorganic fibers are volatized or burned away when the knit article isexposed to a high temperatures (e.g., 300 degrees Celsius or higher; 500degrees Celsius or higher). In some implementations, the continuousload-relieving process aid strand 120, when made of organic fibers, maybe chemical fugitive, i.e., the organic fibers are dissolved ordecomposed when the knit article is exposed to a chemical treatment.

In some implementations, the continuous load-relieving process aidstrand 120 is a metal or metal alloy. In some implementations forcorrosion resistant applications, the continuous load-relieving processaid strand 120 may comprise continuous strands of nickel-chromium basedalloys, such as alloys comprising more than 12% by weight of chromiumand more than 40% by weight of nickel (e.g., Inconel® alloys, Inconel®alloy 718), nickel-chromium-molybdenum based alloys, such as alloyscomprising at least 10% by weight of molybdenum and more than 20% byweight of chromium (e.g., Hastelloy), aluminum, stainless steel, such asa low carbon stainless steel, for example, SS316L, which has highcorrosion resistance properties. Other conductive continuous strands ofmetal wire may be used, such as, for example, copper, tin or nickelplated copper, and other metal alloys. These conductive continuousstrands may be used in conductive applications. In implementations wherethe continuous load-relieving process aid strand 120 is a multifilament,the individual filaments of the multifilament may each have a diameterfrom about 50 micrometers to about 300 micrometers (e.g., from about 100micrometers to about 200 micrometers).

The continuous load-relieving process aid strand 120 and the continuousceramic strand 110 may both be drawn into a knitting system through asingle material feeder together or “plated” in the knitting systemthrough two material feeders to create the desired knit fabric with thecontinuous load-relieving process aid strand 120 substantially exposedon one face of the fabric and the continuous ceramic strand 110substantially exposed on the opposing face of the fabric.

FIG. 2 is an enlarged partial perspective view of a multicomponentstranded yarn 200 including the continuous ceramic strand 110 served(wrapped) around the continuous load-relieving process aid strand 120according to implementations described herein. The continuousload-relieving process aid strand 120 is typically under tension duringthe knitting process while reducing the amount of tension that thecontinuous ceramic strand 110 is subjected to during the knittingprocess. This reduction in tension typically leads to reduced breakageof the continuous ceramic strand 110.

The continuous ceramic strand 110 is typically wrapped around thecontinuous load-relieving process aid strand 120 prior to being drawninto the knitting system. The continuous ceramic strand 110 wrappedaround the continuous load-relieving process aid strand 120 may be drawninto the knitting system through a single material feeder to create thedesired knit fabric.

A serving process may be used to apply the continuous ceramic strand 110to the continuous load-relieving process aid strand 120. Any devicewhich provides covering to the continuous load-relieving process aidstrand 120, as by wrapping or braiding the continuous ceramic strand 110around the continuous load-relieving process aid strand 120, such as abraiding machine or a serving/overwrapping machine, may be used. Thecontinuous ceramic strand 110 can be wrapped on the continuousload-relieving process aid strand 120 in a number of different ways,i.e. the continuous ceramic strand 110 can be wrapped around thecontinuous load-relieving process aid strand 120 in both directions(double-served), or it can be wrapped around the continuousload-relieving process aid strand 120 in one direction only(single-served). Also the number of wraps per unit of length can bevaried. For example, in one implementation, 0.3 to 3 wraps per inch(e.g., 0.1 to 1 wraps per cm) are used.

FIG. 3 is an enlarged partial perspective view of a multicomponentstranded yarn 300 including the continuous ceramic strand 110, thecontinuous load-relieving process aid strand 120 and a metal wire 310prior to processing according to implementations described herein. Asdepicted in FIG. 3, the multicomponent stranded yarn 300 is atri-component stranded yarn. The metal wire 310 provides additionalsupport to the continuous ceramic strand 110 during the knittingprocess. The continuous load-relieving process aid strand 120 may be apolymeric monofilament as described herein. The continuousload-relieving process aid strand 120 and the continuous ceramic strand110 may be both drawn into the knitting system through a single materialfeeder and “plated” together with the metal wire 310 which is drawn intothe system through a second material feeder to create the desired knitfabric.

Similar to the previously described metal alloy materials of thecontinuous load-relieving process aid 120, the metal wire 310 maycomprise continuous strands of nickel-chromium based alloys (e.g.,Inconel® alloys, Inconel® alloy 718), nickel-chromium-molybdenum basedalloys, aluminum, stainless steel, such as a low carbon stainless steel,for example, SS316L, which has high corrosion resistance properties.However, other conductive continuous strands of metal wire could beused, such as, copper, tin or nickel plated copper, and other metalalloys, for example.

In implementations where the continuous load-relieving process aidstrand 120 is heat fugitive (e.g., removed via a heat cleaning process),the metal wire 310 is typically selected such that it will withstand theheat cleaning process. In implementations where the metal wire 310 is amonofilament, the process aid strand may have a diameter from about 100micrometers to about 625 micrometers (e.g., from about 150 micrometersto about 250 micrometers). In implementations where the metal wire 310is a multifilament, the individual filaments of the multifilament mayeach have a diameter from about 10 micrometers to about 50 micrometers.In some implementations, the metal wire 310 is knit into the knit fabricin a soft-tempered state and later heat hardened after the desired shapeof the final product is achieved.

FIG. 4 is an enlarged partial perspective view of another multicomponentstranded yarn 400 including the continuous ceramic strand 110 servedaround the continuous load-relieving process aid strand 120 and themetal wire 310 according to implementations described herein. Asdepicted in FIG. 4, the multicomponent stranded yarn 400 is atri-component stranded yarn. The continuous load-relieving process aidstrand 120 is a polymeric monofilament as described herein. Thecontinuous ceramic strand 110 served around the continuousload-relieving process aid strand 120 are both drawn into the knittingsystem through a single material feeder and “plated” together with themetal wire 310 which is drawn into the system through a second materialfeeder to create the desired knit fabric.

FIG. 5 is an enlarged perspective view of one example of amulticomponent yarn 510 in a knit fabric 500 that includes a wire inlay520 integrated with the knit fabric 500 according to implementationsdescribed herein. The wire inlay 520 depicted in FIG. 5 is aligned withthe knit direction of the knit fabric 500. The wire inlay 520 isperiodically integrated with the knit fabric 500 to provide additionalstiffness and strength to the knit fabric 500. In some implementations,the wire inlay 520 is interwoven with the knit fabric 500. The knitfabric 500 is a weft knitted structure with a horizontal row of loopsmade by knitting the multicomponent yarn 510 in a horizontal direction(i.e., the knit direction). The wire inlay 520 is a continuous inlayincluding straight wire segments 530 a-530 h with alternating curvedwire segments 540 a-540 g connecting each straight wire segment to anadjacent straight wire segment (for example, straight wire segment 530 aand straight wire segment 530 b are connected by curved wire segment 540a). Each straight wire segment 530 a-530 h of the wire inlay 520 isaligned parallel to the knit direction of the multicomponent yarn 510.

The wire inlay 520 may have variable spacing to account for regionswhich require more or less stiffness. For example, wire inlay 520 mayhave uniform or non-uniform spacing between adjacent straight wiresegments. In the implementation depicted in FIG. 5, the wire inlay 520has uniform spacing between the adjacent straight wire segments of thewire inlay 520. One or multiple feeds of wire inlays can be used tocreate the desired architecture of the final component.

FIG. 6 is an enlarged perspective view of yet another example of a knitfabric 600 that includes a multicomponent yarn 510 and a wire inlay 620integrated with the knit fabric 600. The knit fabric 600 is aweft-knitted structure with a horizontal row of loops made by knittingthe multicomponent yarn 510 in a horizontal direction (i.e., the knitdirection). The knit fabric 600 is similar to knit fabric 500 depictedin FIG. 5 except that the wire inlay 620 includes straight wire segments630 a-630 h that are angled relative to the knit direction of the knitfabric 600, straight wire segments 640 a-6401 that are aligned with theknit direction of the knit fabric 600, and curved wire segments 650a-650 c.

The wire inlay 620 is a continuous inlay including straight wiresegments 640 c and 640 d aligned with the knit direction, straight wiresegments 640 f and 640 g aligned with the knit direction, and straightwire segments 640 i and 640 j aligned with the knit direction withalternating curved wire segments 650 a, 650 b and 650 c connecting eachstraight wire segment to an adjacent straight wire segment (i.e.,straight wire segment 640 c and straight wire segment 640 d areconnected by curved wire segment 650 a). Each straight wire segment 640c, 640 d, 640 f, 640 g, 640 i and 640 j of the wire inlay 620 is alignedparallel to the knit direction of the multicomponent yarn 510.

The wire inlay 620 further includes angled straight wire segment 630 awhich connects aligned straight wire segments 640 a and 640 b, angledstraight wire segment 630 b which connects aligned straight wiresegments 640 b and 640 c, angled straight wire segment 630 c whichconnects aligned straight wire segments 640 d and 640 e, angled straightwire segment 630 d which connects aligned straight wire segments 640 eand 640 f, angled straight wire segment 630 e which connects alignedstraight wire segments 640 g and 640 h, angled straight wire segment 630f which connects aligned straight wire segments 640 k and 640 l, angledstraight wire segment 630 g which connects aligned straight wiresegments 640 j and 640 k, and angled straight wire segment 630 h whichconnects aligned straight wire segments 640 k and 640 l.

As discussed herein, the wire inlay 620 may have variable spacing,uniform spacing, or both to account for regions which require more orless stiffness. As depicted in FIG. 6, the wire inlay 620 may havevariable spacing to account for regions which require more or lessstiffness. For example, the spacing between each pair of parallelaligned straight wire segments, for example, 640 c and 640 d, 640 b and640 e, 640 a and 640 f, increases as each pair of parallel alignedstraight wire segment moves away from each curved wire segment 650 a-650c. One or multiple feeds of the wire inlay 620 can be used to create thedesired architecture of the final product.

FIG. 7 is an enlarged perspective view of yet another example of a knitfabric 700 that includes a multicomponent yarn 510 and multipleoverlapping wire inlays 620, 720 integrated with the knit fabric 700according to implementations described herein. The knit fabric 700 is aweft-knitted structure with a horizontal row of loops made by knittingthe multicomponent yarn 510 in a horizontal direction (i.e., the knitdirection). The knit fabric 700 is similar to knit fabrics 500 and 600depicted in FIG. 5 and FIG. 6 except that the knit fabric 700 includesoverlapping wire inlays 720 and 620. Wire inlay 620 and 720 havesegments aligned with the knit direction of the knit fabric 700.

The wire inlay 720 is a continuous inlay including straight wiresegments 722 a-722 c with alternating curved wire segments 724 a and 724b connecting each straight wire segment to an adjacent straight wiresegment (i.e., straight wire segment 722 a and straight wire segment 722b are connected by curved wire segment 724 a). Each straight wiresegment 722 a-722 c of the wire inlay 720 is aligned parallel to theknit direction of the multicomponent yarn 510. The spacing betweenadjacent straight wire segments of the wire inlay 720 is depicted asuniform. However, in some implementations, spacing between adjacent wiresegments of the wire inlay 720 may be variable to account for regionswhich require more or less stiffness.

The wire inlays 520, 620 and 720 may be composed of any of theaforementioned metal or ceramic materials. The wire inlays 520, 620 and720 typically comprise a larger diameter material (e.g., from about 300micrometers to about 3,000 micrometers) that either cannot be knit or isdifficult to knit due to the diameter of the wire inlay and the gauge ofthe knitting machine. However, it should be understood that the diameterof the material that can be knit is dependent upon the gauge of theknitting machine and as a result different knitting machines can knitmaterials of different diameters. The wire inlays 520, 620 and 720 maybe placed in the knit fabric 500, 600, 700 by laying the wire inlays520, 620 and 720 in between adjacent stitches for an interwoven effect.

The multicomponent yarn 510 may be any of the multicomponent yarnsdepicted in FIGS. 1-4. Although FIGS. 5-7 depict a jersey knit fabriczone, it should be noted that the depiction of a jersey knit fabric zoneis only exemplary and that the implementations described herein are notlimited to jersey knit fabrics. Any suitable knit stitch and density ofstitch can be used to construct the knit fabrics described herein. Forexample, any combination of knit stitches, e.g., jersey, interlock,rib-forming stitches, or otherwise may be used.

Although FIGS. 5-7 depict a weft-knitted structure, it should beunderstood that the implementations described herein may be used withother knit structures including, for example, warp-knitted structures.In a warp-knitted fabric, where the knit direction is vertical, the wireinlays may be positioned normal to the knit direction. It should also beunderstood that the wire inlay designs depicted in FIGS. 5-7 are onlyexamples, and that other wire inlay designs may be used with theimplementations disclosed herein. For example, in some implementationswhere segments of the wire inlay are angled relative to the knitdirection, the angled wire segments of the inlay may be positioned at a2 degree to 60 degree angle relative to the knit direction (e.g., at a 5degree to 30 degree angle relative to the knit direction; at a 9 degreeto 20 degree angle relative to the knit direction).

FIG. 8 is a process flow diagram 800 for forming a thermal sealingmember according to implementations described herein. At block 810, theknit fabric is formed. In some implementations, a continuous ceramicstrand and a continuous load-relieving process aid strand areconcurrently knit to form a knit fabric. The continuous ceramic strandand the continuous load-relieving process aid strand may be aspreviously described above. The strands may be concurrently knit on aflat-knitting machine, a tubular-knitting machine, or any other suitableknitting machine. The continuous ceramic strand and the continuousload-relieving strand may be simultaneously fed into a knitting machinethrough a single material feeder to form a multicomponent yarn. Inimplementations where the continuous ceramic strand is wrapped aroundthe continuous load-relieving process aid strand (e.g., as depicted inFIG. 2 and FIG. 4), the continuous ceramic strand may be wrapped aroundthe continuous process aid strand prior to simultaneously feeding thecontinuous ceramic strand and the continuous load-relieving process aidstrand into the knitting machine. A serving machine/overwrapping machinemay be used to wrap the ceramic fiber strand around the continuousload-relieving process aid strand. Although knitting may be performed byhand, the commercial manufacture of knit components is generallyperformed by knitting machines. Any suitable knitting machine may beused. The knitting machine may be a single double-flatbed knittingmachine.

In some implementations where the multicomponent stranded yarn furthercomprises a metal alloy wire the bi-component yarn may be fed through afirst material feeder and the metal alloy wire may be simultaneously fedthrough a second material feeder to form the knit fabric. The strandsmay be concurrently knit to form a single-layer. The metal alloy wiremay be knit in a soft-tempered state which is later hardened by a heathardening process.

In some implementations, a wire inlay is added to the knit fabric. Thewire inlay may be any of the aforementioned metal or ceramic materials.In implementations that contain both a metal alloy wire that is co-knitand a wire inlay, the wire inlay has a larger diameter than the metalalloy wire. The wire inlay typically comprises a larger diametermaterial (e.g., from about 300 micrometers to about 3,000 micrometers;from about 400 micrometers to about 700 micrometers) that either cannotbe knit or is difficult to knit due to the diameter of the wire inlayand the gauge of the knitting machine. However, it should be understoodthat the diameter of the material that can be knit is dependent upon thegauge of the knitting machine and as a result different knittingmachines can knit materials of different diameters. The wire inlay maybe placed in the knit fabric by laying the wire inlay in betweenopposing stitches for an interwoven effect.

In some implementations where a tubular-knitting technique is used, oneor more alloy wires can be floated across opposing needle beds, whichcan provide additional stiffness and support after the seal is expandedto shape and heat hardened.

At block 820, the knit fabric is formed into the desired shape of thefinal component. The desired shape is typically formed while the metalalloy wire and fabric integrated inlay are in a soft formable state. Theknit fabric can be laid up into a preform or fit on a mandrel to formthe desired shape of the final component.

At block 830, the insulation material is optionally added to theinterior of the formed component. Any insulation material capable ofwithstanding desired temperatures may be used. Exemplary insulationmaterials include fiberglass and ceramics. Alternatively, other widelyavailable high temperature materials such as zirconia, alumina, aluminumsilicate, aluminum oxide, and high temperature glass fibers may beemployed. In some implementations, the insulation material is stitchedto the knit fabric. The insulation material may be added at any timeduring formation of the component. For example, the insulation materialmay be added prior to shaping the knit fabric into the component orafter the knit fabric is shaped into the final component. In someimplementations, where the knit fabric is formed using atubular-knitting process, the insulation may be inserted into the tubeduring knit fabrication.

In some implementations, the knit fabric is stitched together to formthe final component. The knit fabric is typically stitched together toform the final component while the metal alloy wire and the wire inlayare in a soft formable state. However, in some implementations, the knitfabric may be stitched together after the metal alloy wire and the wireinlay are hardened.

At block 840, the formed component is heat treated. In implementationswhere no metal alloy is present in the knit fabric, the ceramic-basedfiber may be heat cleaned and heat treated to the manufacturer'sspecifications. This heat treatment process removes any sizing on thefiber, as well as removing the process aid fiber. In implementationswhere the metal alloy is present, the metal is heat hardened to standardspecifications. The heat hardening cycle also serves to remove thesizing on the ceramic-based fiber as well as the processing aid. Inimplementations where the process aid is a sacrificial process aid, theknit fabric is exposed to a process aid removal process. Depending uponthe material of the process aid, the process aid removal process mayinvolve exposing the knit fabric to solvents, heat and/or light. In someimplementations where the process aid is removed via exposure to heat(e.g., heat fugitive), the knit fabric may be heated to a firsttemperature to remove the load-relieving process aid. It should beunderstood that the temperatures used for process aid removal processare material dependent.

In some implementations, the knit fabric is exposed to a strengtheningheat treatment process. The knit fabric may be heated to a secondtemperature greater than the first temperature to anneal the ceramicstrand. Annealing the ceramic strand may relax the residual stresses ofthe ceramic strand allowing for higher applied stresses before failureof the ceramic fibers. Elevating the temperature above the firsttemperature of the heat clean may be used to strengthen the ceramic andalso simultaneously strengthen the metal wire if present. Afterelevating the temperature above the first temperature, the temperaturemay then be reduced and held at various temperatures for a period oftime in a step down tempering process. It should be understood that thetemperatures used for the strengthening heat treatment process arematerial dependent.

In one exemplary implementation where the process aid is Nylon 6,6, theceramic strand is Nextel™ 312, and the metal alloy wire is Inconel® 718,after knitting, the knit fabric is exposed to a heat treatment processto heat clean/burn off the Nylon 6,6 process aid. Once the Nylon 6,6process aid is removed, a strengthening heat treatment that bothInconel® 718 and Nextel™ 312 can withstand is performed. For example,while heating the material to 1,000 degrees Celsius the Nylon 6,6process aid burns off at a first temperature less than 1,000 degreesCelsius. The temperature is reduced from 1,000 degrees Celsius to about700 to 800 degrees Celsius where the temperature is maintained for aperiod of time and down to 600 degrees Celsius for a period of time.Thus simultaneously annealing the Nextel™ 312 ceramic while grain growthand recrystallization of the Inconel® 718 wire occurs. Thus simultaneousstrengthening of the metal wire and subsequent heat treatment of theceramic are achieved.

The knit fabric may be impregnated with a selected settable impregnatewhich is then set. The knit fabric may be laid up into a preform or fitinto a mandrel prior to impregnation with the selected settableimpregnate. Suitable settable impregnates include any settableimpregnate that is compatible with the knit fabric. Exemplary suitablesettable impregnates include organic or inorganic plastics and othersettable moldable substances, including glass, organic polymers, naturaland synthetic rubbers and resins. The knit fabric may be infused withthe settable impregnate using any suitable liquid-molding process knownin the art. The infused knit fabric may then be cured with theapplication of heat and/or pressure to harden the knit fabric into thefinal molded product.

One or more filler materials may also be incorporated into the knitfabric depending upon the desired properties of the final knit product.The one or more filler materials may be fluid resistant. The one or morefiller materials may be heat resistant. Exemplary filler materialinclude common filler particles such as carbon black, mica, clays suchas e.g., montmorillonite clays, silicates, glass fiber, carbon fiber,and the like, and combinations thereof.

In addition to the continuous ceramic strand, the knit fabric mayfurther comprise a second fiber component. The second fiber componentmay be selected from the group consisting of: ceramics, glass, minerals,thermoset polymers, thermoplastic polymers, elastomers, metal alloys,and combinations thereof. The continuous ceramic strand and the secondfiber component can comprise the same or different knit stitches. Thecontinuous ceramic strand and the second fiber component may beconcurrently knit in a single-layer. The continuous ceramic strand andthe second fiber can comprise the same knit stitches or different knitstitches. The continuous ceramic strand and the second fiber may be knitas integrated separate regions of the final knit product. Knitting asintegrated separate regions may reduce the need for cutting and sewingto change the characteristics of that region. The knit integratedregions may have continuous fiber interfaces, whereas the cut and sewninterfaces do not have continuous interfaces making integration of theprevious functionalities difficult to implement (e.g., electricalconductivity). The continuous ceramic strand and the second fibercomponent may each be inlaid in warp and/or weft directions.

The knit fabrics described herein may be knit into multiple layers.Knitting the knit fabrics described herein into multiple layers allowsfor combination with fabrics having different properties (e.g.,structural, thermal or electric) while maintaining peripheralconnectivity or registration within/between the layers of the overallfabric. The multiple layers may have intermittent stitch or inlaidconnectivity between the layers. This intermittent stitch or inlaidconnectivity between the layers may allow for the tailoring offunctional properties/connectivity over shorter length scales (e.g.,<0.25″). For example, with two knit outer layers with an interconnectinglayer between the two outer layers. The multiple layers may containpockets or channels. The pockets or channels may contain electricalwiring, sensors or other electrical functionality. The pockets orchannels may contain one or more filler materials.

The one or more filler materials may be selected to enhance the desiredproperties of the final knit product. The one or more filler materialsmay be fluid resistant. The one or more filler materials may be heatresistant. Exemplary filler material include common filler particlessuch as carbon black, mica, clays such as e.g., montmorillonite clays,silicates, glass fiber, carbon fiber, and the like, and combinationsthereof.

FIG. 9 is a schematic cross-sectional view of an exemplary thermalsealing member 900 according to implementations described herein. Thethermal sealing member 900 is a p-type bulb seal formed from tab portion910 that is coupled to a bulb portion 920. In some implementations, boththe tab portion 910 and the bulb portion 920 are made from the knitfabric described herein. In some implementations, the bulb portion 920is further filled with insulating material 924 (e.g., fiberglass,ceramic, etc.). Of course it should be noted that in someimplementations, not only the bulb portion 920 but also the tab portion910 is at least partially filled with a thermally insulating material.In some implementations, the tab portion 910 is sewn (here, viastitching 930) or otherwise coupled to the bulb portion 920 to completea pliable (typically manually deformable) seal. In some implementationsone or more additional external layers 934 may be added to the thermalsealing member 900 for a variety of purposes, for example, increaseddurability, increased heat resistance, or both.

While the exemplary bulb seal of FIG. 9 is drawn with certainproportions, it should be appreciated that numerous modifications arealso contemplated. For example, and with further reference to the crosssectional view of the bulb seal in FIG. 9, the tab portion may extendsignificantly further to the left to have a width that is up to 2-fold,up to 5-fold, and even up to 10-fold (or even more) than the width ofthe bulb portion. Similarly, the bulb portion may extend significantlyfurther to the right to have a width that is up to 2-fold, up to 5-fold,and even up to 10-fold (or even more) than the width of the tab portion.Moreover, it should be noted that in some implementations, additional(e.g., second, third, fourth, etc.) tab portions are provided to thebulb portion, wherein the additional tab portions may extend into thesame direction or in opposite directions. Likewise, where desirable, oneor more bulb portions may be coupled to the tab portion(s), especiallywhere the end surface is relatively large. Therefore, it should berecognized that in some implementations, the bulb seal includes multiplebulb portions that are most preferably formed from a single sheet (e.g.,a double bulb seal). In such alternative structures, the bulb portionsare preferably sequentially arranged, but may (alternatively oradditionally) also be stacked. Thus, seals are also contemplated inwhich at least one of the bulbs is filled with a different insulatingmaterial than the remaining bulbs (e.g., to accommodate to differentheat exposure).

FIGS. 10A-10B are schematic cross-sectional views of another thermalsealing member 1000 according to implementations described herein. Thethermal sealing member 1000 is an omega-type bulb seal formed from abulb portion 1010 and a split base 1020. In some implementations, boththe bulb portion 1010 and the split base 1020 are made from the knitfabric described herein. The outer configuration of the split base 1020defines a seat that fits within and mates with a channel 1016 to providefirm mechanical seating and support. Although such channels are widelyused for mounting bulb seals, these channels are not required for sealstructures in accordance with the implementations described hereinbecause a wide range of other expedients for mounting or positioning theseal structure can be used. In some implementations, the bulb portion1010 is further filled with insulating material 1024 (e.g., fiberglass,ceramic, etc.). In some implementations one or more additional externallayers 1034 may be added to the thermal sealing member 1000 for avariety of purposes, for example, increased durability, increased heatresistance, or both.

FIG. 10B is a cross-sectional view of the thermal sealing member 1000mounted between opposing surfaces. In FIG. 10B, the thermal sealingmember 1000 is mounted between a firewall 1012 which may be assumed forthis example to be the forward part of an aircraft body, and an opposingmember 1014 which in this instance is a portion of an engine nacellefacing and spaced apart from the firewall 1012. The firewall 1012includes the recessed channel 1016 for receiving the split base 1020 ofthe thermal sealing member 1000. The thermal sealing member 1000 isseated within and positioned relative to the recessed channel 1016 andthe opposing member 1014.

FIG. 11A-11B are schematic cross-sectional views of another thermalsealing member 1100 according to implementations described herein. Thethermal sealing member 1100 is an M-type or heart shaped type bulb sealformed from a bulb portion 1110 and a split base 1120. The bulb portion1110 has a concave portion 1106 for mating with an opposing convexsurface. In some implementations, both the bulb portion 1110 and thesplit base 1120 are made from the knit fabric described herein. Theouter configuration of the split base 1120 defines a seat that fitswithin and mates with a channel 1116 to provide firm mechanical seatingand support. Although such channels are widely used for mounting bulbseals, these channels are not required for seal structures in accordancewith the implementations described herein because a wide range of otherexpedients for mounting or positioning the seal structure can be used.In some implementations, the bulb portion 1110 is further filled withinsulating material 1124 (e.g., fiberglass, ceramic, etc.). In someimplementations one or more additional external layers 1134 may be addedto the thermal sealing member 1100 for a variety of purposes, forexample, increased durability, increased heat resistance, or both.

FIG. 11B is a cross-sectional view of the thermal sealing member 1100mounted between opposing surfaces. In FIG. 11B, the thermal sealingmember 1100 is mounted between a firewall 1112 which may be assumed forthis example to be the forward part of an aircraft body, and an opposingmember 1114 which in this instance is a portion of an engine nacellefacing and spaced apart from the firewall 1112. The firewall 1112includes the recessed channel 1116 for receiving the split base 1120 ofthe thermal sealing member 1100 while the opposing member 1114incorporates a convex groove 1118 opposite to and paralleling thechannel 1116 for mating with the concave portion 1106 of the thermalsealing member 1100. The thermal sealing member 1100 is seated withinand positioned relative to the recessed channel 1116 and the opposingmember 1114.

It should be understood that the implementations described herein arenot limited to the seal geometries depicted in FIGS. 9-11. In additionto the seal geometries depicted in FIGS. 9-11, the seals can becurvilinear or discrete and can also incorporate other geometricfeatures such as holes, additional flanges, or overlapping flaps forattachment to other structures, for insulation enclosure, or both.Furthermore, one or more additional external layers may be added to theseal designs described herein for a variety of purposes, for example,increased durability, increased heat resistance, or both.

Fabrication and qualification tests performed on samples based on theimplementations described herein demonstrated increased performance overcurrent baselines, including compression set, abrasion, and fire/flametests on integrated Nextel™ 312 ceramic fiber and Inconel® alloy 718 andp-type bulb seal samples. Multilayer current state of the art thermalbarrier seals were compared with the integrated knit ceramic (Nextel™312) and metal alloy (Inconel® alloy 718) seals formed according toimplementations described herein. The integrated knit ceramic sealsemployed a co-knit Nextel™ 312 and small diameter Inconel® alloy 718wire along with a larger diameter Inconel® alloy 718 wire inlay.

Compression set testing was performed at 800 degrees Fahrenheit for 220hours while compressed to 30%. All samples had less than 1% heightdeflection post-test. Compression set testing was also performed at1,000 degrees Fahrenheit for 168 hours while compressed to 30%. In thishigh temperature compression test, all samples had less than 5%compression set post-test. Under the same compression set testingconditions, the current state of the art thermal barrier seal becameplastically compressed with greater than 10% compression set whichresulted in gaps and ultimately failure as a thermal and flame barrier.No failures occurred during initial abrasion testing with 5,000 cyclesat 30% compression. A nacelle vibration profile was run on samples ofthe hybrid thermal barrier seals described herein. The hybrid thermalbarrier seals survived the complete 5 hour nacelle vibration profilewhen compressed to 30% and held in contact with titanium and stainlesssteel wear plates. The same profile, compression and wear interfaceswere run on the current state of the art thermal barrier seals withfailures occurring 3 hours into the run. The backside of the sealremained intact under 200 degrees Fahrenheit when a 3,000 degreesFahrenheit torch was applied to the front at a one inch offset from theseal for a period of five minutes. No failures occurred under firetesting with a flame at 2,000 degrees Fahrenheit for a period of 15minutes. Furthermore, no flame penetration was observed during testingand no backside burning occurred when the flame was shut off after aperiod of 15 minutes.

To understand the effect of inlay wires on the seal compressionbehavior, load versus deflection tests were performed on different inlayarchitectures (i.e. no inlay/coil, aligned-only inlay, angled-onlyinlay, and aligned and angled inlay) with variable inlay spacing. Theresults of this study showed that the angled inlays act more like atruss structure, which leads to increases stiffness in seals undercompression, while aligned inlays tend to buckle or shift undercompression. This study demonstrated that an angled inlay with 0.5″spacing had better compression resistance than the aligned and angledinlay which has more coils per inch but less angled inlay. Therefore,optimized architectures can lead to simpler inlay designs that take lesstime to fabricate, lead to less fiber breakage and have lower weight.

It should be noted that the products constructed with theimplementations described herein are suitable for use in a variety ofapplications, regardless of the sizes and lengths required. For example,the implementations described herein could be used in automotive,marine, industrial, aeronautical or aerospace applications, or any otherapplication wherein knit products are desired to protect nearbycomponents from exposure to volatile fluids and thermal conditions.

While the foregoing is directed to implementations of the presentdisclosure, other and further implementations of the disclosure may bedevised without departing from the basic scope thereof, and the scopethereof is determined by the claims that follow.

What is claimed is:
 1. A thermal sealing member, comprising: asingle-layer ceramic-based knit fabric, comprising: a continuous ceramicstrand; a continuous load-relieving process aid strand, wherein thecontinuous ceramic strand serves the continuous load-relieving processaid strand; and a first metal alloy wire, wherein the continuous ceramicstrand, the continuous load-relieving process aid strand, and the firstmetal alloy wire are knit to form the single-layer ceramic-based knitfabric.
 2. The thermal sealing member of claim 1, further comprising asecond metal alloy wire, wherein the second metal alloy wire is inlayedinto the ceramic-based knit fabric.
 3. The thermal sealing member ofclaim 2, wherein a diameter of the second metal alloy wire is greaterthan a diameter of the first metal alloy wire.
 4. The thermal sealingmember of claim 2, wherein the second metal alloy wire is alignedparallel with a knit direction of the single-layer ceramic-based knitfabric.
 5. The thermal sealing member of claim 2, wherein the secondmetal alloy wire is angled relative to a knit direction of thesingle-layer ceramic-based knit fabric.
 6. The thermal sealing member ofclaim 1, wherein the single-layer ceramic-based knit fabric is aweft-knitted fabric.
 7. The thermal sealing member of claim 1, whereinthe single-layer ceramic-based knit fabric is a warp-knitted fabric. 8.The thermal sealing member of claim 1, further comprising insulationmaterial positioned in an interior of the thermal sealing member.
 9. Thethermal sealing member of claim 1, wherein the thermal sealing member isselected from an M-shaped double-blade bulb seal, an omega-shaped bulbseal, and a p-shaped bulb seal.
 10. The thermal sealing member of claim1, wherein the thermal sealing member has a reversible elasticdeflection of at least 10% to at most 80% of a height of the thermalsealing member.
 11. The thermal sealing member of claim 1, wherein thecontinuous load-relieving process aid strand is a polymeric material.12. A method of forming a thermal sealing member, comprising:simultaneously feeding a continuous ceramic strand and a continuousload-relieving process aid strand through a single material feeder and afirst metal alloy wire through a second material feeder; concurrentlyknitting the ceramic strand, the continuous load-relieving process aidstrand and the first metal alloy wire to form a single-layerceramic-based knit fabric, wherein the metal alloy wire is in asoft-tempered state; and forming the single-layer ceramic-based knitfabric into the shape of the thermal sealing member.
 13. The method ofclaim 12, further comprising interweaving a second metal alloy wire intothe ceramic-based knit fabric.
 14. The method of claim 13, wherein adiameter of the second metal alloy wire is greater than a diameter ofthe first metal alloy wire.
 15. The method of claim 13, wherein thesecond metal alloy wire is aligned parallel with a knit direction of thesingle-layer ceramic-based knit fabric.
 16. The method of claim 13,wherein the second metal alloy wire is angled relative to a knitdirection of the single-layer ceramic-based knit fabric.
 17. The methodof claim 12, further comprising adding insulation material to aninterior of the shaped thermal sealing member.
 18. The method of claim12, wherein concurrently knitting is performed using either aflat-knitting process or a tubular-knitting process.
 19. The method ofclaim 12, wherein the single-layer ceramic-based knit fabric is formedusing a weft-knitting process or a warp-knitting process.
 20. The methodof claim 12, further comprising heat treating the formed thermal sealingmember to harden the first metal alloy wire.